Abstract
A nucleosome histone core model is presented which is compatible with experimental data. The model consists of 28 α-helices located as predicted by others 1–4. The histone wheel resembles the one proposed by Klug et al. 5 Most of the helices are packed nearly parallel to the DNA superhelical axis, forming a bandoleer-like structure. About 10 to 20% of the nucleosomal phosphates may be neutralized by positively charged residues in the α-helices. Disregarding the charge of the NH 2-terminals, this is sifficient for the thermodynamic stability of the nucleosome under physiological conditions. The electrostatic charge on the protein surface is assumed to be relatively fixed due to the participation of the corresponding side chains to the hydrophobically packed helices. Thus, DNA wrapping appears to be determined by the core histones not by the histone NH 2-terminals.
Published Version
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